Process of making the piperidine salt of pentamethylene-dithiocarbamic acid



I No Drawing.

acting with piperidine' upon carbon-bisulfide: in the presence of a solvent; itgives prac-J 25 rectly' an accelerator which is stable'under Patented Sept;

v A UNITED STATE-S DU 20m DE NEMOURS & COMPANY, or wrLMme'ro r, DELAWAR A conromyrron OF'DELAWARE Y y p PROCESS or MAKI G THE PIPERIDINE SALT or 5 cAnBA IcAcID'p,

, The piperidin'e salt of pentamethylenedithio-carbamic acid was amongstthe first organic substances used in the acceleration of the vulcanization of caoutchouc substances 5 and due to its most powerful action it is still used todayiin theproduction of numerous" rubber articles. This acceleratorhaving the following formula i Y has commonly been producedby the direct action of carbon bis ulfide upon purepiperldine and purification of the crude reaction product. It was found, however, that technica lor impure piperidinesdo not give a good yield of the salt and produce compounds containing slight amounts of impurities which in a very unfavorable way affect the stability r of the accelerator. I

My invention relates to a process of retically theoretical yields and produces diordinary conditions of storing, shipping and handling in the mill room of rubber factories ,It comprises the use of solvents in whlch both raw materials, their impurities and byproducts of the reaction are easily soluble, whereas the desired piperidine salt ofthe pentamethylene-dithioecarbamic acid is exceedingly little soluble therein; I

Such solvents are found amongst the valiphatic and alicyclic hydrocarbons which are liquid at ordinary temperatures andboll below about 250 C. Q

; No generic scientific name seems to have been adopted for non-'benzenoid cyclic hydrocarbons which are partly unsaturated, such as cyclopentene, eyclohexene, methylcyclopentene and others,-and I desire it to be un derstood that for convenience sake, the term Valicyclic'as used herein is meant to lnclude such partiallv unsaturated non-benzenoid,

"cyclic hydrocarbons' I Some of the aliphaticiand alicyclichydm Y carbons have in late "years become commerciallyi available throughf various processes ance of my invention. a My novel processcomprlses essentially'disrmvrAMErHYLm-mrnm Application filed m y 11, 1929. Seria1 N0: 36'2;456.;

formed' with carbons.

GEORGE LUTZQ Q ROCKY :axvnnonro; assxeiromny MEsrIE AssIGNME rsQ'ro-n: 1.

including hydrogenation of benzenoid h :31

h P ess of my invention does.

Such mixtures obtainedin the petroleum industry are sometimes referred to asparafiin hydrocarbons-of petroleum origin and are better; known} commercially as gasolines.

As is well known, tained from various sources, suchas from casing head gas rectification, from cracking processes, from direct distillation of crude petroleum. etc, and 'whilethe various gaso lines are of somewhat different compositions,

theyare all mixtures of aliphatic hydrocarbons containing more or:-less alicyclic prodnets, and are all available for theiperformsolving either oneof-the two raw materials. piperidine andcarbonbisulfide in the desired solvent, and adding the other material; the

reaction between the ,piperidine and the car'- bon-bisulfidewis strongly xothermicfthe heat generated is absorbed by the solvent and'-ex-,

cessive rise in temperature is.prevented,, the reaction proceeds gradually and the piper-idine salt crystallizes out. usually in the form of beautiful needles. The salt is. separated from the supernatant liquor by any'wen known means,

recovered contains the impurities of the piperidine and :of the carbon-bisulfide,-' but it'can be used for succeeding batches,' with such additions of solvent as required to compensatefor mechanical losses, until too much of the impurities haveaccumulated. r

; Thesolvent is then recovered by distilla gasolines are today ob and dried, preferably at low temperature, or under vacuum, The solvent r ground, a practically colorless p'ovvde'n vvhich' is very stable under ordinary conditions and has-the characteristicaccelerating'propertles V a ofthe salt preparedin the usual way; I Technical piperidine. is available in a qual-' 1Q ity containing only about 80% actual piper1-' dine, the balance'being gpyri'dine and its'h0ino logues, piperidine "homologues and water. My novel process is particularly a dapted to p the use of such technical piperidine; I 85'partsbyvveight of technical, 80%,piperi-- dine were" added co-1600 parts by Weight, of gasoline. 38]Oarts by weight of carbonbiwe sulfide 'vvere sloyvlyrun into; this solutions, The temperature of the solution roseand the 26 piperidinesaltofithepentamethylene-dithio dried'for aboutianhour at'.aboutf35 C. ,The

' carbamicacid precipitated in the form-of I fine, practically colorlessneedless After coolto room temperature, the crystals were '7 o filtered ofi, vvashedvvitha' little gasoline and a resulting salt was after grinding eminently suited as a vulcanization accelerator; 'Therecovered solvent was made upYto 1600 parts'g'85 parts technical piperidine dissolved Q0 therein', 35partscarbon-bisulfid added nd I a h the same procedure as" described above continued." This was repeatedfour times more before thesolvent as'discardedQ Thepiperi 1 I dine salt resulting from su'ch operationsiwas, f f, Q] 7 5 afterigrin'ding, directly usable asaovulcanii zationcaccelerator II. a '1 novel process isgs'iniilarlyg performed 1 vwhen using other liquida'liphaticforjalioyclic' hydrocarbons ,ormixtures thereof boilingbe in low 250LC. assolvents. Hexahvdrobenzene 4 p is'for instance vviell suited fori this purpose I but in'vievv of itsfsomevvhat higih price itsre-- a coveryyvouldbe necessaryandit could hard- J 1: i i v mp t 'w fi eche p andsasilv av il: 1 i able. parafiin (hydrocarbonsof petroleum W V origin Icl ai1 n:; I, v 1'.- he process of contacting piperidine and carbonrbisulfide' in a solvent comprising fill) a hydrocarbon of th e 'goup constituted by it y i I aliphatic and alicyclic hydrocarbonsyvhich j are inert with respect to theureactants, liquid at ordcinary'temperature and boil'belowlabout 1 2. The process of contacting pi'p'eridine f and carbon-bisulfidein a solvent'consisting I of liquid parafiin'hydrocarbons'ofpetroleum origin 'boiling'belovv: about 250 0.1 1

1;. "3. 'The process: of making the 'piperidine M In testirnony ewhereof l afiix my signature} 0 salt ofr pentaIneth-ylene-dithioacarbamic acid which comprisesadding piperidine and carbon-bisulfide to gasolineand separating the r I precipitated salt ,from'the, solvent. 1

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